Explain the concept of a modular multilevel converter (MMC) with fault-tolerant control for AC power systems.
1 Answer
Corona discharge is an electrical phenomenon that occurs when the electric field strength at the surface of a conductor is high enough to ionize the surrounding air, causing a partial breakdown of the air insulation. In high-voltage AC power transmission systems, corona discharge can lead to power losses, radio interference, and even damage to equipment. To minimize or prevent corona discharge in AC power transmission, the following techniques and measures are employed:
Increased Conductor Size: Using larger diameter conductors reduces the electric field intensity at the surface of the conductor, making it less likely for corona discharge to occur.
Bundled Conductors: Grouping multiple conductors together in a bundle reduces the effective diameter of the combined conductors, which helps to reduce the electric field strength and the likelihood of corona discharge.
Smooth Conductor Surface: A smooth and polished conductor surface reduces the likelihood of ionization and corona formation compared to a rough surface.
Usage of Special Conductor Shapes: Certain conductor designs, such as hollow conductors or twisted conductors, can help distribute the electric field more evenly and reduce corona discharge.
Optimal Conductor Spacing: Ensuring the proper spacing between conductors and between conductors and other components (like supporting structures) can help maintain lower electric field intensities and reduce the risk of corona discharge.
Reducing Operating Voltage: Operating the transmission line at lower voltages decreases the electric field strength and reduces the likelihood of corona discharge. However, this may not always be practical due to the need for long-distance power transmission.
Use of Corona Rings: Corona rings or grading rings are attached to high-voltage conductors at certain intervals. These rings distribute the electric field more evenly, preventing localized high field strengths that could lead to corona discharge.
Optimal Weather Conditions: Corona discharge is more likely to occur under adverse weather conditions, such as high humidity, rain, or fog. Monitoring weather conditions and adjusting transmission parameters when needed can help mitigate corona effects.
Insulating Spacer Arrangement: Placing insulating spacers or discs between conductors or between conductors and supporting structures can help maintain proper spacing and reduce the chances of corona discharge.
Advanced Insulation Materials: Using advanced insulation materials for conductors, insulators, and support structures can help reduce corona discharge by improving the overall insulation system's performance.
It's important to note that a combination of these techniques is often used in high-voltage AC power transmission systems to effectively minimize or prevent corona discharge and its associated issues. The specific approach taken depends on factors such as the voltage level of the transmission line, environmental conditions, and available technology.
Increased Conductor Size: Using larger diameter conductors reduces the electric field intensity at the surface of the conductor, making it less likely for corona discharge to occur.
Bundled Conductors: Grouping multiple conductors together in a bundle reduces the effective diameter of the combined conductors, which helps to reduce the electric field strength and the likelihood of corona discharge.
Smooth Conductor Surface: A smooth and polished conductor surface reduces the likelihood of ionization and corona formation compared to a rough surface.
Usage of Special Conductor Shapes: Certain conductor designs, such as hollow conductors or twisted conductors, can help distribute the electric field more evenly and reduce corona discharge.
Optimal Conductor Spacing: Ensuring the proper spacing between conductors and between conductors and other components (like supporting structures) can help maintain lower electric field intensities and reduce the risk of corona discharge.
Reducing Operating Voltage: Operating the transmission line at lower voltages decreases the electric field strength and reduces the likelihood of corona discharge. However, this may not always be practical due to the need for long-distance power transmission.
Use of Corona Rings: Corona rings or grading rings are attached to high-voltage conductors at certain intervals. These rings distribute the electric field more evenly, preventing localized high field strengths that could lead to corona discharge.
Optimal Weather Conditions: Corona discharge is more likely to occur under adverse weather conditions, such as high humidity, rain, or fog. Monitoring weather conditions and adjusting transmission parameters when needed can help mitigate corona effects.
Insulating Spacer Arrangement: Placing insulating spacers or discs between conductors or between conductors and supporting structures can help maintain proper spacing and reduce the chances of corona discharge.
Advanced Insulation Materials: Using advanced insulation materials for conductors, insulators, and support structures can help reduce corona discharge by improving the overall insulation system's performance.
It's important to note that a combination of these techniques is often used in high-voltage AC power transmission systems to effectively minimize or prevent corona discharge and its associated issues. The specific approach taken depends on factors such as the voltage level of the transmission line, environmental conditions, and available technology.